1. Field of the Invention
The present invention relates to a solid electrolytic capacitor and a manufacturing method thereof.
2. Description of the Background Art
Niobium has a dielectric constant about 1.8 times as large as that of tantalum which is a material for conventional solid electrolytic capacitors. Therefore, Niobium has been attracted much attention as a material for next-generation, high capacitance solid electrolytic capacitors.
However, when the solid electrolytic capacitor is subjected to high heat in a reflow soldering step, oxygen in a dielectric layer including niobium oxide is partly diffused into the anode and the thickness of the dielectric layer is reduced. As a result, leakage current is more likely to be caused in the dielectric layer.
In one suggested solid electrolytic capacitor, a niobium nitride region is formed in a niobium oxide layer as a dielectric in order to reduce changes in capacitance caused by oxygen diffusion in the reflow soldering step during mounting the solid electrolytic capacitor (see JP-11-329902-A).
In the conventional solid electrolytic capacitor provided with the nitride as described above, however, leakage current still cannot be sufficiently reduced.